Turbochargers having such a housing unit are known in the art, for example, from U.S. Pat. Nos. 4,780,054 or 5,146,752.
The requirements as to emission reduction are growing, as is known. One of the causes of increasing ecological damage, that is to be avoided, is the so-called “blow-by” effect wherein exhaust gas from the turbine housing flow to the suction side of the compressor. Numerous suggestions have been made to prevent such flow. On the other hand, more and more fun mobiles come onto the market which are not thought to run on normal streets, but driven in the middle of cross-country, for example through watercourses and ponds. Certainly, the exhaust gas pressure prevents, in general, penetrating of water, but under normal conditions the vehicle should not be left in water when the motor is switched off.